Lab 8
Exploring MicroInvertebrate Diversity
OBJECTIVES:
 Explore the vast diversity of soil micro-organisms.
 Use a dichotomous key to identify these organisms.
 Explore the relationship between habitat and diversity.
PRELAB:
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Before you come to lab read this entire Lab 8 and be ready to begin the exercises.
Several days prior to lab, someone will collect samples for analysis.
ASSIGNMENT:
 Your instructor will tell you what to hand in.
MATERIALS:
Burlese funnel system
dissecting microscope
compound microscope
vial containing specimens in alcohol
guide to common soil animals
dissecting probes/needles
shallow containers for viewing
squirt bottle of alcohol
PROCEDURES:
**NOTE: Some of these organisms are so small that you will have a hard time seeing
them with the naked eye! In fact, it will even be difficult seeing some under the
dissecting microscope!
1. Obtain your sample vials, dissecting microscopes, a shallow container for viewing,
and one or two dissecting needles/probes. As a team, you will need to split up the
identifying.
2. Turn off the light of the Burlese apparatus.
3. While saving the wire mesh or cheesecloth, empty the contents of the funnel in the
trash. Return the funnel and mesh.
4. Swirl the vial to get as many of the organisms in suspension as possible, then pour the
contents into the shallow container. If you need to, use the alcohol squirt bottles to wash
out any organisms that remain in the sample vial.
5. Place the shallow container under the microscope and sort the organisms. With the
dissecting needle/probe, move similar looking organisms together in groups.
6. Use the guide to identify what you can.
7. In Table 1, keep track of the number or each type of organism. Use “tick marks” to
keep track, instead of counting.
A. Sort the organisms by moving similar looking organisms together in groups
with the dissecting needle/probe. Count the number of individuals in each group,
using “tick marks” to keep track instead of counting if there are many
individuals, and counting up the tick marks later.
B. One group member scans the shallow container and calls out the identity of
organisms they see while another group member keeps track of them by using tick
marks. Count up the tick marks when finished.
8. After you have finished, add up the total number of individuals for each type of
organism you found.
Table One: Soil Organism Data
Type of Animal
Number of Individuals
(tick marks)
Thysanura
(bristletails)
Collembola
(springtails)
Thysanoptera
(thrips)
Protura
Pseudoscorpions
Ticks
Mites
Centipedes
Millipedes
Spiders
Insect Larvae
Beetles
Nematode worms
Others
ANALYSIS OF SOIL ORGANISM DATA:
Total Number Calculated Density
Observed
(#/cm2)
1. Calculate the estimated density of each taxon, and for all taxa combined. To do so,
you need an estimate of the amount of area sampled when we collected the leaf litter
sample. We estimate that the area sampled was 225 cm2. Calculate the density of each
taxon by dividing the number of individuals (the abundance) for the taxon by the total
area sampled. Enter the density in Table one.
2. With your lab group, review your notes from the site your leaf litter was collected.
Present a description of your habitat and the densities of organisms observed to the class
as directed by your instructor. If your data differs from that of other groups, can you
formulate a hypothesis to explain the difference? How might you go about testing your
hypothesis?
NOTES FOR PRESENTATION:
CLEAN-UP:
1. Dispose of all disposable materials appropriately.
2. Replace all other materials to their proper location (i.e. where you got them).
3. Wipe of your workspace.
Thanks for leaving the lab neat and clean!